Umayyad Open Cistern, Amman

The “Castle Ground Tank” or the Umayyad Pool is an archaeological ground tank dating back to the Umayyad period of rule. It is located in the center of the Jordanian capital, Amman, specifically within the walls of the city's castle, which also contains many Umayyad monuments and other civilizations that came to the city thousands of years ago. It was built in the eighth century AD, specifically in the year 730 AD, in an area adjacent to the Umayyad Palace, to be one of several reservoirs in the castle, but it is the largest in size. The reservoir was designed to be the main water source for the Umayyad palace. It is about 5 meters deep and 17.5 meters in diameter, and contains more than 1,370 cubic meters of water. Rainwater was fed into the reservoir through an internal channel, collected in other reservoirs, and then returned and poured into the large reservoir, that is, there was a process of water reproduction. There were also channels to extract water from the pond for use, and a small well was discovered on the northern side of the pond, and this well is the same depth as the pond itself. There is also a channel connecting the bottom of the well with the bottom of the pond, so that the water level in the pond is the same as in the well. It is also possible to go down to the bottom of the tank via stairs for the purpose of maintenance. In the middle of the tank is a pole, which is believed to have been used to measure the water level. So far, there is no information to prove that the pool was covered or not, or any architectural elements that show such a thing, and this area, in order to be roofed, must have supports, columns or arches, so it is likely that the pool was exposed and not cover it. It is noteworthy that the Jordanian Ministry of Tourism and Antiquities restored the building in the early nineties of the last century to be in the current form.

As you leave Audience Hall and Throne Room turn left and follow a narrow passage you come our facing huge circular well like structure built in the ground. Looked really impressive as a water storage tank. The ides of "rain harvesting " and the capacoty, "water proof plaster" WOW ! Mind boggling. This is what the information board displayed next to it has to say about the open Cistern. " Open Cistern. "Birka". Ca 730 AD. This uncovered cistern referred to as "Birka" or "Shrij" in Arabic, measures 58 feet in diameter and its stone walls are up to 8 feet thick. The interior surface was covered with waterproof layer of plaster, and you can see traces of this ancient layer near staircase. The sloped floor collected unwanted silt at the bottom. Up to 48000 cubic feet of water could be collected in the cistern. It was diverted there from roofs of surrounding buildings and paved surfaces through channels feeding in to it from north and west side of the cistern. A column in the center measured water level. The cistern supplied water to baths, latrines and other areas of settlement. Located part way up the cistern wall, a hole leads to a shaft that discharges water through east fortification wall."

A big structure for water storage. Indicates how developed those people were regarding understating of water management system.

Large circular uncovered water cistern capable of hosting an impressive 1370 cubic meters of runoff water. Water was diverted here from nearby buildings' roofs and paved floors through a series of vertical and horizontal conduits. You can see the feeders in the north and west sides of the cistern. A column was used to measure the water level in the middle of the bottom floor which is sloped to collect sand and mud deposits. As of autumn 2021, the water measuring column has been partially restored and reerected adding beauty to the overall visual presentation of the cistern. Stairs circling around the walls provided access to the bottom for servicing. The tank supplied water to the nearby baths and latrines rather than for drinking.

The cistern is a 5m deep water tank. For me it was one of the most interesting sites. There is a staircase leading to the bottom of the tank. it was used to gather rainwater for the inhabitants of the citadel.